HED announced the Jet 180, a new rear wheel rim with a depth of 180mm.
The Jet 180 is specifically designed for athletes competing at the Ironman World Championships in Kona, Hawaii. Full rear disc wheels have been banned in the Kona due to safety concerns in windy conditions.
The 180mm deep flange has a maximum outer width of 32.5mm and an inner width of 21mm.
It is tubeless compatible and available in disc and rim brakes. The claimed weight of the wheel is 1,229g in disc brakes, or 1,258g in rim brakes.
HED has not announced pricing yet, but indicated that they are currently available within four to six weeks of ordering, with a limited number of wheels available for the 2022 Ironman World Championships in Kona.
How fast is the HED Jet 180?
At the time of writing, HED has not published any claims or performance data comparing it to other, more conventional aero wheels in its range, such as the Jet 6 or the Jet Disc.
However, the intent of the wheel appears to be to simulate the surface area of the disc’s wheel rim as much as possible, within the limits imposed by the Kona race organizers.
The significantly increased tire surface area for disc wheels and rims like this one helps improve aerodynamic efficiency in two ways, depending on how the wind affects them.
In a headwind or headwind, a deep rim or hard disk surface helps keep airflow attached to the wheel for as long as possible. This reduces turbulent airflow and reduces drag.
In a tailwind or crosswind, the surface area of the rim acts as a sail, helping to propel the rider forward more efficiently.
Can this rim be used on a front wheel?
In theory, yes, although HED is only offering it as a rear wheel drive at the moment.
Neither the ITU (International Triathlon Federation) nor the UCI (Union Cycliste Internationale, the world cycling governing body) set specific limits on front wheel rim depth in single time trials.
However, Britain’s time trial governing body, sets limits on the depth of the leading edge. Its rules state that the front wheel “must have at least 45 percent of the surface area open,” although it’s unclear how this would be measured in an event.
However, regardless of the regulations, it is likely that the primary problem that prevents people from applying is concerns about dealing with it.
An ultra-deep rim might theoretically be faster than a shallow rim (everything else being equal), but if it confidently prevents you from maintaining an ideal aerodynamic position on the bike because it continues to catch wind, it’s probably slower overall.
However, today’s wider and more complex profiles generally offer significantly improved handling characteristics compared to tires of the past.
As a result, specialists in time trials and triathlons routinely push the chuck for additional gains.
The Aerocoach’s AEOX Titan front wheel, which is 100mm deep, has seen extensive use by some of the world’s best testing professionals in recent years, such as Filippo Ganna, Geraint Thomas and Wout van Aert.
Rumors swirled that at least one WorldTour team had tested a front disc wheel for road trial use, and he didn’t rule out the possibility of using it in a racing scenario.
So, if HED were to make this rim available for use as a front wheel drive, you can be sure it would spark some interest among marginal gain chasers.
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